//DT crc数据校验函数
exports.crc32 = function (x) {
    var i, len, str;
    var crcbits, crcnumh, crcnum, crcbitcount;
    var strdata, strcrc, strdata0;
    var crccode = '04C11DB7';     //crc权值
    crcbits = 32;
    crcnum = crcbits / 4;
    crcnumh = crcnum - 8;
    len = x.length;
    if (len > 0) {
        if (crcbits <= 32) {
            strdata0 = inttohex(0, crcnum);
        }
        else {
            strdata0 = inttohex(0, crcnumh) + inttohex(0, 8);
        }
        strcrc = 'FFFFFFFF';//初值
        str = x;
        len = str.length;
        crcbitcount = len * 4;//位域4
        for (i = 0; i < len; i += crcnum) {
            strdata = str.substr(i, crcnum);//明文
            strcrc = get_crc_string(strdata, strcrc, crccode, strdata0, crcbits, crcbitcount);//CRC4~64
            crcbitcount -= 4 * crcnum;
        }
        return strcrc;
    }
}

var _auchCRCHi = new Array(
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
    0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
    0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
    0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
    0x80, 0x41, 0x00, 0xC1, 0x81, 0x40);
var _auchCRCLo = new Array(
    0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
    0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
    0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
    0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
    0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
    0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
    0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
    0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
    0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
    0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
    0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
    0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
    0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
    0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
    0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
    0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
    0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
    0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
    0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
    0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
    0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
    0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
    0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
    0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
    0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
    0x43, 0x83, 0x41, 0x81, 0x80, 0x40);


exports.crc16_modbus = function (buffer, length) {
    var crcHi = 0xff;
    var crcLo = 0xff;
    for (var i = 0; i < length; i++) {
        var crcIndex = crcHi ^ buffer[i];
        crcHi = (crcLo ^ _auchCRCHi[crcIndex]);
        crcLo = _auchCRCLo[crcIndex];
    }
    return (crcHi << 8 | crcLo);
}

exports.crc16 = function (str) {
    var buf = Buffer.from(str);
    //var buf = Buffer.from(Array(0x01, 0x03, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00));
    var crc = 0xFFFF;

    for (var i = 0; i < buf.length; i++) {
        crc = (crc >> 8) ^ buf[i];
        for (var j = 0; j < 8; j++) {
            var temp = crc & 0x01;
            crc >>= 0x0001;
            if (temp == 0x01) {
                crc ^= 0xA001;
            }
        }
    }
    return crc;
}

//不足位数 前面补0
exports.addzero = function () {
    var tbl = [];
    return function (num, n) {
        var len = n - num.toString().length;
        if (len <= 0) return num;
        if (!tbl[len]) tbl[len] = (new Array(len + 1)).join('0');
        return tbl[len] + num;
    }
}();

function inttohex(num, size) {
    var str, ptr, len, i, j, s;
    if (num >= 0) str = num.toString(16);
    else {
        num = -num;
        i = num >> 16;
        j = num & 0xffff;
        i ^= 0xffff;
        j ^= 0xffff;
        j++;
        if (j > 0xffff) {
            j = 0;
            i++;
        }
        str = i.toString(16);
        ptr = j.toString(16);
        j = ptr.length;
        if (j < 4) while (4 > j++) ptr = '0' + ptr;
        str = str + ptr;
    }
    len = str.length;
    if (len >= size) str = str.substr(len - size, size);
    else {
        while (size > len++) str = '0' + str;
    }
    return str.toUpperCase();
}

function AsciiToHex(asciistr) {
    var hexstr;
    var i, num;
    hexstr = "";
    for (i = 0; i < asciistr.length; i++) {
        num = asciistr.charCodeAt(i);
        num &= 0x7f;
        hexstr += inttohex(num, 2);
    }
    return hexstr;
}

function hextoint(string) {
    return parseInt(string, 16);
}

function get_crc_string(crcdatastr, crcinitstr, crcploystr, crcstopstr, crcbit, crccount)//CRC4~64
{
    var i, crc, hcrc, bit, size, len, crcstr = "";
    var crcdata, crcinit, crcploy, crcstop, hcrcdata, hcrcinit, hcrcploy, hcrcstop;

    size = crcbit / 4;
    len = crcdatastr.length * 4;
    for (i = 0; i < (size - len / 4); i++) crcdatastr = crcdatastr + "0";//补0
    if (crccount == 0 || crccount >= crcbit) {
        len = crcbit;
        crccount = len;
    }
    else len = crccount;
    crcdata = hextoint(crcdatastr);//强制大端
    crcinit = hextoint(crcinitstr);
    crcploy = hextoint(crcploystr);
    crc = crcdata ^ crcinit;
    bit = 1 << (crcbit - 1);//端点
    for (i = 0; i < len; i++) {
        if (crc & bit) {
            crc <<= 1;
            crc ^= crcploy;
        }
        else crc <<= 1;
    }
    crcstop = hextoint(crcstopstr);
    crc ^= crcstop;
    crcstr = inttohex(crc, size);
    return crcstr;
}


//校验和取反,只保留1字节-new 喷嘴喷吹控制器使用
exports.checksum = function (x) {
    let value=0;
    for(let i=0;i<x.length/2;i++){
        value+=parseInt('0x'+x.substr(i*2,2));
        // console.log(parseInt('0x'+x.substr(i*2,2)));
    }
    // console.log(value)
    value=value.toString(16).substr(-2);
    value=0xFF-parseInt('0x'+value);
    // console.log(value)
    value='00'.substr(value.toString(16).length)+value.toString(16);
    // console.log(value)
    return value.toString(16);
}